Comparative and developmental studies of AMP-deaminase imply that this enzyme has a significant regulatory function. The long-term goal of the proposed research is to determine the molecular bases of developmental changes in AMP-deaminase in erythrocytes. The short-term objectives are to: isolate this enzyme from adult chicken erythrocytes; define the regulatory properties of AMP-deaminases from adult chicken muscle and erythrocytes; determine the molecular bases of its isoenzymes; describe the time course of appearance of AMP-deaminase activity in erythrocytes from control and anemic chickens; determine whether increases in the activity of this enzyme in deaminase activity are associated with modified catalytic (regulatory) properties; and assess the roles of altered rates of synthesis and degradation in developmental changes in erythrocyte deaminase.